The present disclosure relates to a vehicle drain hole structure, and particularly relates to an improved vehicle drain hole structure (e.g., of the type formed in a plastic part of a vehicle's induction system) that prevents or reduces the likelihood of a liquid film forming thereacross.
Vehicles are known to employ any number of drain holes for preventing water from accumulating and/or for directing accumulated water out of the vehicle or components thereof. One area where drain holes are used is the vehicle's induction system. For example, a vehicle's induction system may include a serpentine or circuitous air passageway upstream of an engine intake manifold that includes a low section acting as a fluid trap, which allows any objects or moisture drawn into the air passageway to collect. A drain hole can be provided in the low section for directing water/moisture out of the inductive system and thereby preventing the same from entering the vehicle's engine intake manifold.
Vehicle drain holes, including those used in a vehicle's induction system, have been formed with various cross-sectional shapes, e.g., round, square, etc. However, conventional vehicle drain holes usually have a cross-sectional area that remains constant along an entire depth of the drain hole. One problem associated with these types of conventional drain hole configurations (i.e., those having a constant cross-sectional area) is that a liquid film sometimes forms across the hole, presumably due to surface tension, which is disadvantageous because it interferes with water or moisture draining through the hole.
For example, FIG. 4 illustrates a conventional vehicle drain hole 60 through wall 62. As shown, the cross-sectional area of the hole 60 remains constant as the hole extends through the wall 62 from wall surface 64 to wall surface 66. Wall 62 could be part of an air intake tube for directing air to a vehicle's engine intake manifold, for example. As can be seen from FIG. 4, a liquid film 68 can form across the hole 62 and prevent drainage through the hole 60 due to water or moisture clinging to sidewall 70 of the hole (i.e., surface tension).
Drain holes for non-vehicle applications have sometimes used tapered drain holes, but the drain hole structures forming such drain holes tend to be more complex or involved. For example, these types of drain hole structures can include added components that extend the axial or longitudinal length of the drain structure. In addition, these types of drain holes can be formed by structures that are particular to the environment in which the drain hole is used. For example, a drain hole provided in a pneumatic line may be configured with a tapered drain hole that increases in area from a first end disposed within or at an inner surface of a pneumatic line toward a second end to minimize the amount of compressed air lost through the drain hole.